A composite optical device including two optical sections bonded to each other and a relief pattern (a diffraction surface) formed on the interface between the two optical sections is conventionally known (see, for example, Patent Document 1). This composite optical device can reduce the dependency on a wavelength of the diffraction surface, and is regarded useful as a device for obtaining high diffraction efficiency in light of a wavelength different from the blaze wavelength particularly for an optical system using light of plural kinds of wavelength bands such as a camera optical system.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2001-249208